Apparatus for heating with natural gas



Feb- 21, 1967 M. LEvEQuE: ETAL APPARATUS FOR HEATING WITH NATURAL GAS 2Sheets-Sheet 1 Filed Jan. 14, 1964 F l'qj /N VENToRSZ MAURscE LEVEQUC- dMARCH L Cour/*uv rheir Horny Feb. 2l, 1967 M. LEVEQUE ET AL 3,304,987

APPARATUS FOR HEATING WITH NATURAL GAS Filed Jan. 14, 1964 zsheets-sheet 2 )NVENTORS MAURICE LEVEQUE md MARCEL coa/TAM) UnitedStates Patent F 3,304,987 APPARATUS FOR HEATING WITH NATURAL GAS MauriceLeveque, Issy-les-Moulineaux, and Marcel Cou- The present inventionrelates in a general Way to the heating of industrial furnaces, ovensand like enclosures by means of natural gas and more particularly gashaving a high content of methane or other hydrocarbons.

The flame of a natural gas normally comprises carbonio gas and steamwhose radiation factors are l-ow. Further, the proportion of dry sm-okeper unit volume of natural gas is very distinctly greater than that oftown gas. Consequently, owing to these factors, the substitution ofnatural gas for townA gas in gas heating units results in a marked dropin the eciency of these units.

The object of the invention is to provide an improved process of puttingnatural gas in combustion which increases the radiation power of theflame and consequently affords an improved transmission of the heat tothe cold source. One of the objects of the invention is in particular toobtain, by the application of this improved process, an improved totalenergetic eticiency of a heated enclosure in permitting substitution ofnatural gas for town gas or fuel oil for the heating of this enclosurewithout need to modify the geometric characteristics of this enclosure.

For this purpose, the invention concerns imparting the necessaryluminosity to the flame and obtaining a flame having the dimensionalcharacteristics appropriate to the enclosure in whi-ch the flame must bedeveloped.A

It is known that hydrocarbons, such as methane, can be disassociated bythermal cracking with formation of particles of carbon and soot which,when they are in suspension in a flame, impart high luminosity to thelatter.

The process for improving the characteristics of a natural ygas llamewhich is one of the objects of the present invention comprises producinga jet of natural gas and subjecting said jet of natural gas on theupstream side of the mixing `point of said jet with a jet of comburentgas, to the action of a high temperature resulting in at least a partialcracking of the peripheral Zone of said jet of natural gas.

This high temperature is of the order of at least 900 C. and is obtainedby the heating of a hollow refractory body through which the jet ofnatural gas travels, said heating being obtained by means of anauxiliary jet formed by drawing off a small proportion of natural lgaswhich is mixed prior to its ignition with a comburent gas or mixture(which is not necessarily oxygen and can be for example air) inaccordance with the necessary theoretical proportion for the combustionof this auxiliary jet bearing in mind the composition of said naturalgas.

The amount of natural gas drawn off can be of the order of 3% of themain jet ow.

Another object of the invention is to provide an improved burner adaptedfor the use of natural combustible gas, said burner comprising incombination a main axial 43,304,987 Patented Feb. 2l, 1967 I CC conduitadapted to be connected to a natural :gas supply conduit, the mainconduit communicating with a refractory jet in the form of a cylindricalsleeve coaxial with the main conduit, an annular auxiliary conduitcoaxial with the main conduit and communicating with the sleeve in anannular zone which is contiguous with the inner face of the sleeve andwith the end of the main conduit, the auxiliary cond-uit being adaptedto be connected to a supply conduit supplying a mixture of natural gasand comburent gas (for example air), said burner being adapted to bemounted axially in the entrance of a radiating opening with whichcommunicate the conduits supplying air and preferably hot air.

Another object of the invention is to provide a heating unit for afurnace or like enclosure said unit comprising an air injenctionopening, a burner of the type dened hereinbefore mounted axially in theentrance of said opening, a natural gas supply conduit connected to themain conduit of the burner and to a source of natural gas, a mixer ofair and natural gas connected, on the one hand, to sources of air `andnatural gas and, on the other hand, to the annular conduit of theburner, and a device supplying air to said opening, said devicepreferably comprising an apparatus heating air by direct heating or byrecuperation which preheats said air supply.

Further features and advantages of the invention will be apparent fromthe ensuing description, with reference to the accompanying drawings towhich the invention is in no way limited.

In the drawings:

FIG. l is an axial sectional view of a burner according to theinvention;

FIG. 2 is an elevational view of said burner taken at to FIG. l, and

FIG. 3 is a view, partly in perspective Iand partly in section, of aheating unit for a furnace which employs the process according to theinvention.

In the, embodiment shown in FIGS. l and 2, a natural gas burneraccording to the invention, generally designated by the referencecharacter 1, comprises a generally annular shaped metal collar 2 whichhas fixing holes 2a and in which is disposed a jet 3 composed of arefractory material and constituting a sleeve having two cylindricalportions 3a, 3b separated by a shoulder 3c, the portion 3a which is ofsmaller diameter extending forwardly of the mounting face 2b of thecollar. This sleeve is held in position by a cylindrical case 4 securedto the collar 2 by a screwthreaded engagement, welding or other means.The jet 3 and case 4 are separated by an insulating gasket 5. The case 4comprises a pipe 4a adapted to be connected to a conduit 6.

The jet or sleeve 3 has an axial cylindrical chamber 7 Whose wallcomprises deep grooves, for example helical grooves 7a. This chambercomprises an upstream portion 7b of larger diameter in which is disposeda ring 8 whose end 8a of smaller diameter extends into the chamber 7.Formed between the outer face of this ring and the wall of the chamber7, 7a, is a space 9 constituting an annular conduit coaxial with thechamber 7, 7a. 'Ihe ring 8 has an axial conduit in which is disposed anozzle 10 composed of a refractory material and secured to the end of atube 11 which extends through the case 4 through circular coaxialopenings 12a, 12b.

A space 5a formed between the ring 8 and the case 4 permits the annularconduit to communicate with the opening 12a and consequently with theinner chamber of the case 4.

Secured to the case 4 by screwing, welding or other means, is a head 13carrying a base 13a and a pipe 13b adapted to be connected to a conduit14. The inner passage 13c of this pipe communicates with a chamber 13dwhich communicates with the inner cavity 11a of the tube 11. Thecavities 13C, 13d, 11a and the cavity of the nozzle form a main conduitcommunicating with the conduit 14 and the axial part of the chamber 7 ofthe jet 3. The cavity of the pipe 4a, the cavity of the case 4, theopening 12a, the space 5a, and the annular conduit 9 constitute anauxiliary conduit which communicates with the conduit 6 and theperipheral part of the chamber 7, since the outer wall of the annularconduit is constituted by a portion of the wall of the chamber 7 lof thejet 3.

The assembly is completed by the following accessories. The size of theend passage `section of the nozzle 10 is adjusted by a member 15 of ovalor like shape,disposed axially in said nozzle and secured to the end ofa rod 16 which is screwed at 16a in the head 13 and is provided with aregulating wheel 17. A pipe 18 independent of the conduit 14communicates with the latter and tangentially at 18a with the cavity 11aof the tube 11. A tap 19 regulates the flow through this pipe. Theconduit 14 and pipe 18 have been omitted from FIG. 2 for the sake ofclarity.

This burner (FIG. 3) is secured through the medium of its collar 2 tothe outer face of an element 21 of refractory material closing theopening in a heating furnace F and provided with air inlet conduits 22which communicate by way of an annular passageway 22a with the mouth ofthe element 21 at a certain distance inward of the end of the jet 3 ofthe burner, the conduits 22 communicating with an annular chamber 23connected to a heat-insulated pipe 24 which is connected to arecuperation device or regenerator R -fed with air by a fan V and withheat by a smoke pipe T.

Fur-ther, the conduit 14 is connected to a source of natural gas (notshown) which constitutes the heating fuel of the furnace; the conduit 6is connected to an air and gas mixer M fed with air by a conduit A andwith natural gas by a conduit G connected to said source of na-turalgas.

The apparatus operates in the following manner;

Whereas the major part of the natural gas to be burnt is supplied by theconduit 14 to the main conduit and reaches the nozzle 10, a smallproportion of this gas (for example 3% of the total supply) is suppliedto the mixer M where it is mixed with air in proportions correspondingto the theoretical combustion, bearing in mind the cornposition of the`gas. This mixture is supplied through the conduit 6 and the auxiliaryannular conduitl 9 to a region in the vicinity of the end of the nozzle10 of the main conduit. This mixture is combustible and ignited, but issupplied under such pressure that, firstly, its cir-r culation velocityis higher than the velocity of propagation of the llame in this gaseousmixture and, secondly, the ilarne is stabilized in a position in thevicinity of the end of the auxiliary conduit. This auxiliary combustionperyforms a double function:

(l) This auxiliary combustion heats at high temperature-of the order ofat least 900 C-the peripheral zone of the gas jet which issues from thenozzle and thus results in a partial cracking of this gas; consequently,there are created in the llame in the opening of the element 21 when thegas is mixed with the air issuing from the passageway 22a, particles 'ofcarbon and soot which impart intense luminosity to the flame and thusincrease the transmission of heat by radiation.

(2) Said auxiliary combustion insures a preheating of, for example, 300C. of the whole of the gas jet before its ignition.

It will be observed that:

(a) In the course of its ,passage through the jet 3 the annular flame isdriven in a helical direction by the rubbing of its peripheral zoneagainst the helically ribbed wall of the chamber 7.

(b) The regulating device, constituted by the control wheel 17 and tap19, imparts to the flame dimensional characteristics appropriate tothose of the enclosure F to be heated. The Isetting of the oval valvemember 15 by means of the wheel 17 regulates the length of the flame.The setting of the valve 19 regulates the flow of the tangential jetsupplied by the pipe 18 and consequently the magnitude of the rotarycomponent given in this region to the gas jet in the main conduit;consequently the ilame can be made more or less turbulent or soft.

It will be understood that it is also possible to adjust by means (notshown) the supply of the gas-air mixture to the auxiliary .annularconduit, the velocity of this mixture in the supply conduit and thus thestabilized position of the auxiliary darne. Consequently it is possibleto adjust the degree of the localized high cracking temperature and thedegree of preheating of the llame; this degree depends also on thisadjustment of the temperature of the hot air supplied by the pipe 24.

Although specic embodiments of the invention have been described, manymodifications and changes may be made therein without departing from thescope of the invention as defined in the appended claims.

Having now described our invention what we claim as new and desire tosecure by Letters Patent is:

1. A burner intended to be mounted axially in the entrance of aradiating opening which is provided in an enclosure to be heated andcommunicates with air supply conduits, the burner comprising meansdefining a body in which are provided, a main axial conduit means forsupplying raw natural gas to said main conduit, said conduit meanshaving an outlet end and inlet end, a jet composed of refractorymaterial and in the form of a sleeve which is coaxial with andcommunicates with the main conduit, an annular auxiliary conduit coaxialwith the main conduit and communicating with the sleeve in an annularzone which is contiguous with the inner face of the sleeve and with saidoutlet end of the main conduit, means for supplying a `mixture ofnatural gas and an oxidant to said auxiliary conduit, the burner furthercomprising a main pipe having -one end for connection to a source ofnatural gas and another end communicating with said inlet end of themain conduit, a secondary pipe having one end connected to the main pipeand another end communicating with the interior of and being connectedto said inlet end of the main conduit in such manner as to be tangentwith the main conduit, whereby a portion of said natural gas is suppliedtangentially in the inlet end of the main conduit.

2. A burner intended to be mounted axially in the entrance of aradiating opening which is provided in an enclosure Ito be heated andcommunicates with air supply conduits, the burner comprising meansdefining a body in which are provided, a main axial conduit, means forsupplying natural gas to the main conduit, said means having an outletend and an inlet end, a jet composed of refractory material and in theform of a sleeve which is coaxial with and communicates with the mainconduit, an annular auxiliary conduit coaxial with the main conduit andcommunicating with the sleeve in an annular zone which is contiguouswith the inner face of the sleeve and with said outlet end of the mainconduit, means for supplying a mixture of natural gas and an oxidant tothe auxiliary conduit; the burner further comprising a main pipe havingone end for connection to a source of natural gas and another endcommunicating with said inlet end of the main conduit, a secondary pipehaving one end connected to the main pipe and another end communicatingwith the interior of and being connected to said inlet end of the mainconduit, whereby a portion of said 5 natural gas is suppliedtangentially in the inlet end of 2,167,183 the main conduit, and meansinserted in the secondary 2,188,133 pipe for adjusting the gas owtherethrough. 2,836,481 2,873,174 References Cited by the Examiner 5UNITED STATES PATENTS 180,350 936,781 10/1909` Kemp. 1106 351 1,430,3279/1922 Sauer. 1,686,711 10/1928 Schrader 158-990 2,047,471 7/1936Hepburn et al. 15S-99X 10 2,117,968 5/1938 Lutherer 158-99 6 7/ 1939Naab et =a1. 1/ 1940 Hepburn 126-91 5/ 1958 Hof-stede. 2/ 1959 Capuderet al. 158-7X FOREIGN PATENTS 11/1954 Austria. 7/1955 France.

FREDERICK L. MATTESON, I R., Primary Examiner.

H. B. RAMEY, C. R. REMKE, Assistant Examiners.

1. A BURNER INTENDED TO BE MOUNTED AXIALLY IN THE ENTRANCE OF ARADIATING OPENING WHICH IS PROVIDED IN AN ENCLOSURE TO BE HEATED ANDCOMMUNICATES WITH AIR SUPPLY CONDUITS, THE BURNER COMPRISING MEANSDEFINING A BODY IN WHICH ARE PROVIDED, A MAIN AXIAL CONDUIT MEANS FORSUPPLYING RAW NATURAL GAS TO SAID MAIN CONDUIT, SAID CONDUIT MEANSHAVING AN OUTLET END AND INLET END, A JET COMPOSED OF REFRACTORYMATERIAL AND IN THE FORM OF A SLEEVE WHICH IS COAXIAL WITH ANDCOMMUNICATES WITH THE MAIN CONDUIT, AN ANNULAR AUXILIARY CONDUIT COAXIALWITH THE MAIN CONDUIT AND COMMUNICATING WITH THE SLEEVE IN AN ANNULARZONE WHICH IS CONTIGUOUS WITH THE INNER FACE OF THE SLEEVE AND WITH SAIDOUTLET END OF THE MAIN CONDUIT, MEANS FOR SUPPLYING A MIXTURE OF NATURALGAS AND AN OXIDANT TO SAID AUXILIARY CONDUIT, THE BURNER FURTHERCOMPRISING A MAIN PIPE HAVING ONE END FOR CONNECTION TO A SOURCE OFNATURAL GAS AND ANOTHER END COMMUNICATING WITH SAID INLET END OF THEMAIN CONDUIT, A SECONDARY PIPE HAVING ONE END CONNECTED TO THE MAIN PIPEAND ANOTHER END COMMUNICATING WITH THE INTERIOR OF AND BEING CONNECTEDTO SAID INLET END OF THE MAIN CONDUIT IN SUCH MANNER AS TO BE TANGENTWITH THE MAIN CONDUIT, WHEREBY A PORTION OF SAID NATURAL GAS IS SUPPLIEDTANGENTIALLY IN THE INLET END OF THE MAIN CONDUIT.